Anesthesia ventilator apparatus

ABSTRACT

An improvement is disclosed for anesthesia ventilating apparatus of the type including a patient breathing circuit, a bellows in the breathing circuit which by its expansion and contraction regulates the volume of gas cycled to the patient, a chamber surrounding the bellows, a pneumatic powering system for cyclically pressurizing and depressurizing the chamber to effect expansion and contraction of the bellows, and a highly flexible diaphragm which serves to separate, fluidly, the patient circuit from the pneumatic powering system, yet which transmits a negative pressure signal from the patient upon an attempt to inhale to trigger cycling of the pneumatic system. In the improvement, the highly flexible diaphragm, called a pucker plate, is mounted in an enclosed chamber located exterior of the bellows chamber, preferably above the chamber, and which has only its under surface in communication with the patient circuit, thus precluding moisture from accumulating on the upper surface of the flexible diaphragm, thereby assuring indefinite service without response changes due to the accumulation of such moisture on the flexible diaphragm.

United States Patent [191 u :1 3,841,327 Hay 1 Oct. 15, 1974 ANESTHESIAVENTILATOR APPARATUS apparatus of the type including a patient breathingcir- [75] Inventor, Wayne w. Hay, Madison Wis cuit, a bellows in thebreathing circuit which by its expansion and contraction regulates thevolume of gas [73] Asslgneer 'CO, New York, NY. cycled to the patient, achamber surrounding the bellows, a neumatic owerin s stern for c clicallres- [22] Filed. July 2, 1973 P P g y Y y P surizing and depressurizingthe chamber to effect ex- PP 376,075 pansion and contraction of thebellows, and a highly flexible diaphragm which serves to separate,fluidly, [52] us CL l 128/188 the patient circuit from the pneumaticpowering sys- [51] Int. 1....11111....1.11111111111111111111111111?2am16/00 an ya wanna nananna a naaaava nanal [58] Field of Search 128/188,202, 203, 142.2, the Patient attempt inhale trigger 128/1423 142.4,145.5 145.6 1458 cycling of the pneumatic system. In the improvement,the highly flexible diaphragm, called a pucker plate, is [56] ReferencesCited mounted in an enclosed chamber located exterior of the bellowschamber, preferably above the chamber, 3 046 979 STATES PATENTS andwhich has only its under surface in communica- Andreasen 128/1458Primary ExaminerRichard A. Gaudet Assistant Examiner-Henry J. ReclaAttorney, Agent, or FirmRoger M. Rathbun; E. W. Bopp; H. H. Mathews [57]ABSTRACT An improvement is disclosed for anesthesia ventilating tionwith the patient circuit, thus precluding moisture from accumulating onthe upper surface of the flexible diaphragm, thereby assuring indefiniteservice without response changes due to the accumulation of suchmoisture on the flexible diaphragm.

5 Claims, 2 Drawing Figures PATEME um 5 1914 sum 1 or 2 FIG.1

ANESTHESIA VENTILATOR APPARATUS BACKGROUND OF THE INVENTION Thisinvention relates generally to anesthesia apparatus, and morespecifically relates to the anesthesia ventilating apparatus which arein common use for providing adequate ventilating for a patient duringsurgery.

The anesthesia ventilating apparatus to which the present invention hasapplication, includes devices which have found wide application inhospital operating rooms and similar environments. These ventilators aredesigned to replace or augment the function of a breathing bag. Inparticular, the said ventilators are designed to either supplement therespiratory effort of a patient who is breathing spontaneously, or in analternate mode of functioning, take over the entire effort ofrespiration for a patient.

Devices of the type cited above commonly utilize a bellows as part ofthe breathing circuit for the apparatus, which bellows is commonlymounted in vertical orientation within a surrounding chamber. Itsdisplacement in an upward (contraction) and downward (expansion)direction serves to control the flow and quantity of gases in thebreathing circuit to the patient. The displacement of the bellows in adownward direction is commonly effected by gravity acting upon a weightmounted within the lower part of the bellows body, and its upwarddisplacement is enabled by pneumatic powering means which pressurizesthe surrounding chamber in which the bellows is mounted. The chamberpressure, so raised, causes contraction of the bellows, thereby forcinggas from the bellows to the patient circuit. Again, the degree of suchpowering pneumatic pressure may be controlled for a specific patientsrequirements.

Depending upon the desired mode of operation for the said ventilatingapparatus, the pneumatic powering pressure for the chamber within whichthe bellows is mounted, may be provided on a predetermined cyclicallytimed basis, or the application of the powering pressure may betriggered by inspiratory effort on the part of the patient, i.e., thepatient draws a slight negative pressure in an attempt to inhale. Forthe latter purposes, it has been common to provide at the bottom of thebellows a very light gauge flexible rubber diaphragm-This flexiblediaphragm is commonly referred to as a pucker plate. In particular, thesaid diaphragm, located interior of the bellows, responds to asufficient inhalation effort on the part of the patient by flexing,whereby a negative pressure is drawn on the opposite side of the puckerplate from the patient, that is, outside the bellows but within thebellows chamber. By this means the negative signal may be transmitted toa sensing device which is fluidly isolated from the patients circuit andthus cannot become contaminated by pathogens or the like within thepatient circuit. The sensing device responds to the slight negativepressure communicated to the chamber to activate a suitable controlvalve in a pneumatic powering system to initiate a cycle of operationfor the ventilator by pressurizing the bellows chamber, thus contractingthe bellows itself.

Unfortunately, the construction described in the preceding paragraph,where the pucker plate is located at the bottom of the bellows, suffersfrom a defect tending to impair long-term efficient operation of theapparatus. That location within the bellows is convenient to isolate thepatient circuit within the bellows from the sensing element, i.e.,exterior of the bellows but within the chamber; however, its particularlocation is unfortunate in that moisture from the patient circuitcollects on the internal surface of the bellows and drains to thebellows bottom, thereby eventually covering the upper surface of puckerplate with moisture and rendering it less sensitive to further attemptsby the patient to inhale.

SUMMARY OF INVENTION Now, in accordance with the present invention, theaforementioned problem with moisture accumulation on the pucker platehas been overcome in an anesthesia ventilating apparatus byrepositioning the highly flexible diaphragm constituting the puckerplate in an upper chamber overlying and exterior of the bellows chamberof the apparatus. The diaphragm is mounted within this upper chamber tofluidly separate first and second gas spaces therein on opposite sidesof the diaphragm. The first gas space is formed underneath the flexiblediaphragm and communicates with the patient circuit. The second gasspace is formed above the flexible diaphragm and communicates with thespace within the bellows chamber external of the bellows and thus to thepneumatic powering system. The relocation, in effect,

creates parallel gas spaces and frees the pucker plate from anysubstantial loading with accumulating moisture within the bellows. Thediaphragm is so mounted within the said upper chamber that the first gasspace communicating with the patient circuit. lies beneath thediaphragm, which is preferaly oriented in a generally horizontaldirection, whereby any moisture in the patient circuit which may contactand condense on the diaphragm forms only on the underside thereof anddrains off harrnlessly. In consequence of these construction features,the sensitivity of the ventilating apparatus to the patients inspiratoryefforts is not impaired, and the apparatus may be operated for extendedperiods of time without changes in the performance characteristics. Atthe same time, the construction utilized is such that the pucker platechamber may be readily opened, in order to gain access to the interiorthereof, for inspecting or servicing the diaphragm and other components.

BRIEF DESCRIPTION OF DRAWINGS The invention is diagrammaticallyillustrated, by way of example, in the drawings appended hereto, inwhich:

FIG. 1 is-an elevational view of the ventilating apparatus constructedin accordance with the present invention; and

FIG. 2 is a vertical cross-sectional view of the ventilating apparatusdepicted in FIG. 1, taken along the line 2-2 thereof.

DESCRIPTION OF PREFERRED EMBODIMENT In FIGS. 1 and 2 herein, there isshown a ventilating apparatus 10 constructed in accordance with thepresent invention. A conventional pneumatic powering system, not shown,may be used which responds to inspiratory effort on the part of apatient by instituting a cycle of operation of the ventilator. Suchcontrol systems are well known and include valving means to sense apredetermined negative pressure in the bellows chamber extern'al of thebellows, whereupon a main valve is actuated to pressurize the bellowscontainer, as will be described. Such apparatus and control means arepresently marketed commercially. Accordingly, these various conventionalportions of the overall ventilator are not illustrated herein, but theirfunction will become clear in the course of the ensuing description. Theventilator apparatus 10, shown, includes a frame 12, including a framecross plate 14, and two or more vertical frame members 16 which engageat their bottom ends with a support base 18 (shown only in part). Frame12 and support base 18 provide support for a bellows chamber 22 which ispreferably formed out of clear cylindrical plastic or the like and maybe enclosed within a cage 20, which is best seen in FIG. 2. The lowerperiphery of cylinder 22 is sealed against the support base 18 by meansof a sealing ring 24 so that the gas volume within the cylinder 22 maynot leak from the ends thereof.

Referring particularly to FIG. 2, it is seen that a control head 26encloses the upper end of cylinder 22, with the walls of the head 26being sealed with the periphery of the upper end of cylinder 22 by meansof sealing ring 28. A depending flange 30 flares outwardly from head 26within cylinder 22, and a bellows 32 is secured at its open upper end tothe flange 30. The open upper periphery of the flexible bellows issealed in gas-tight contact to the head flange 30. Bellows 32 is made ofrubber or other flexible material, and is contractable and expandable ina vertical direction. In particular, in accordance with the well-knownoperation of this type of ventilating apparatus, positive air pressurefrom a pneumatic powering system is introduced to the interior ofcylinder 22 surrounding the bellows 32 to force the bellows 32 tocollapse upwardly, thereby forcing a volume of gas contained within thebellows outwardly through holes 33 and 35 in the head 26 and thencethrough passageways 34 and 31 to the patient breathing circuit via theconduit 36.

The bellows 32 carries at its lowermost convolution a weight of metal orthe like, which functions to return the bellows to its lowermost,expanded position, upon completion of the inspiratory portion of thebreathing cycle. During the expansion of bellows 32, the interior of thecylinder 22 is vented to atmospheric pressure through an exhaust valvein the pneumatic powering system.

in order to regulate the tidal volume or overall linear travel of thebellows, a chain 42 is secured to the bottom of the bellows 32, such asat 44, and thence is led upwardly through opening 46 in head 26 tocylinder 48, which is engaged by pin 50 to rotatable shaft 52. The shaft52 is joumaled in head 26 and may be rotated by the control knob 54,secured to the external portion of shaft 52. Depending on patientrequirements, shaft 52 is rotated to wind chain 42 about the cylinder 48to thereby establish an adjustable limit to set the lowermost travel ofbellows 32. Once set at the desired tidal volume, the control knob 54 isheld by friction through O-ring 56 against flange 58 on head 26 by meansof spring 60. A scale 62 is mounted externally of the apparatus, inorder to provide an indication of the resultant tidal volume to theoperator of the apparatus.

In accordance with the present invention, it will be seen that theuppermost portion of control head 26 is provided with an upstandingcircular shoulder 64 forming at its top a rim 66. A thin flexible rubberdiaphragm 68 is secured across rim 66 and then turned downwardly andsealed about the rim 66 so as to form a first gas space or chamber 70beneath the diaphragm 68. A perforated plate 72 encloses the first gasspace 70 by extending across head 26 beneath the flexible diaphragm 68.The plate 72 has its outer periphery bearing against the internalsurface of head 26 as shown, and is secured by a retaining ring 73.

A second gas space or chamber 74 is formed above the diaphragm 68,enclosed within a cover 76 which is fitted over and sealed to the head26 via sealing ring 78. The cover 76 is held in place by a retainingscrew 82, which is threaded through an opening in cross plate 14, andhas a lower end 84 which bears against a receiving opening in the saidcover 76.

It may now be seen that the cover 76 serves together with portions ofhead 26 to define a pucker plate chamber 86, which chamber is divided bythe flexible diaphragm 68 into a first gas space 70, and a second gasspace 74. It is further seen that the second gas space 74 above thediaphragm 68 communicates via passages 88, shown in shadow, with the gasvolume within cylinder 22 exterior of the bellows 32. Accordingly, itwill be evident that the second gas space 74 and the gas volume withincylinder 22 exterior of bellows 32 are isolated completely from possiblecontamination from the patient circuit. This isolated space may thencommunicate with conventional pressure sensitive control means whichalso will remain free from contamination.

The first gas space 70, on the other hand, is seen to be incommunication, through the head 26, with the conduit 36 by means ofpassageways 34 and 31. Conduit 36 is, in use, coupled to the patientbreathing circuit. It will thus be evident that a negative pressure suchas is induced by a patients inspiratory effort, will be directlycommunicated to the first gas space 70 beneath flexible diaphragm 68.The diaphragm 68 is caused to flex downwardly, thus transmitting thenegative pressure signal to the second gas space 74 above the flexiblediaphragm 68, through passages 88, to the interior of cylinder 22 andthus to a pressure sensitive control means which is then triggered topressurize the interior of cylinder 22 to collapse bellows 32 upwardlyand expel the fluid contained therein to the patient through conduit 36.

Before the increased pressure within cylinder 22 forces bellows 32upwardly, the pressure is also transmitted to the second gas space 74via'passages 88. The increased pressure is then transmitted through aduct 92 to inflatable exhaust valve 38 to close the exhaust valve 38.After the bellows 32 has reached its uppermost contracted position, thepneumatic controller conventionally senses the increased pressure andshifts the ventilator to exhalation phase where the bellows 32 dropsfreely. When the bellows reaches its lower limit the reduced pressure inthe bellows cylinder 22 allows exhaust valve 38 to open and vent thebreathing circuit to atmospheric pressure.

It is again pointed out that the general operational techniques utilizedin the presently depicted apparatus, are conventional in the sense thata flexible diaphragm has been previously used for coupling the pressuresignal induced by the patient's inspiratory effort at the breathingcircuit, to the conventional pneumatic control system which communicateswith the interior of the bellows chamber to effect operation of thebellows.

In accordance with the present arrangement, however, it will be evidentthat such moisture as may be introduced from the patient breathingcircuit will enter the first gas space 70 beneath diaphragm 68, andshould it condense at all on the diaphragm 68, will merely drip from theunder surface thereof and hence have no effect on the sensitivity of thediaphragm. The moisture from the patient circuit thus can only condenseon the underside surface of the pucker plate, yet the pucker plate stillserves to effectively isolate the patient circuit, including the bellowsinterior, from all pneumatic controls used with the ventilator.

While the present invention has been particularly set forth in terms ofspecific embodiments thereof, it will be understood in view of theinstant disclosure, that numerous variations upon the invention are nowenabled to those skilled in the art, which variations yet reside withinthe scope of the instant teaching. Accordingly, the invention is to bebroadly construed, and limited only by the scope and spirit of theclaims now appended hereto.

I claim:

1. In anesthesia ventilating apparatus of the type including a patientbreathing circuit; a bellows in said breathing circuit adapted to expandand contract to cycle gas to the patient circuit, a bellows chambersurrounding said bellows; a pneumatic powering system for cyclicallypressurizing said chamber to cause the expansion and contraction of saidbellows; and a highly flexible diaphragm mounted intermediate the saidpatient circuit and said pneumatic powering system and adapted to bedisplaced by a negative pressure signal from said patient circuit toeffect a negative pressure signal to said pneumatic powering system fortriggering cycling of said pneumatic system; the improvement comprisinga diaphragm chamber containing said flexible diaphragm, said diaphragmseparating said chamber into first and second separate gas spaces, saidfirst gas space being located above said flexible diaphragm andcommunicating with said pneumatic powering system, and said secondchamber being located below said flexible diaphragm and communicatingwith said patient circuit whereby moisture within said patient circuitcollects on the bottom of said flexible diaphragm and drains downwardlytherefrom.

2. Apparatus in accordance with claim 1 wherein said diaphragm chamberis mounted above and exterior of said bellows chamber.

3. Apparatus in accordance with claim 1 wherein said flexible diaphragmis circular and has its periphery sealed to the interior of saidenclosed chamber.

4. An anesthesia ventilator for delivering gas to a patient comprising:

a patient circuit;

a head;

a cylindrical bellows chamber depending from said head, having its upperperipheral rim sealed to said head and being closed at its lower end;

a collapsible bellows suspended within said chamber for delivering fluidto said patient circuit and having its upper open end sealed to saidhead;

a flexible diaphragm mounted on top of said head, having its bottomsurface in communication with said patient circuit, and its top surfacein communication with said bellows chamber, said flexible diaphragmadapted to flex upon sensing a negative pressure in the patient circuitto transmit the negative pressure to said bellows chamber;

a pneumatic powering system communicating with said bellows chamber andadapted to respond to a negative pressure in said bellows chamber topressurize said bellows chamber and thereby force said bellows tocollapse whereby gas within said bellows is forced into the patientcircuit;

normally open valve means venting the patient circuit, said valve meansadapted to sense the increased pressure in said bellows chamber to closesaid valve means.

5. In anesthesia ventilating apparatus of the type including a patientbreathing circuit; a bellows in said breathing circuit adapted to expandand contract to cycle gas to the patient circuit; a bellows chambersurrounding said bellows; a pneumatic powering system communicating withsaid bellows chamber for cyclically pressurizing said chamber to causethe expansion and contraction of said bellows; the improvementcomprising: a diaphragm chamber, a flexible diaphragm separating saidchamber into an upper gas space and a lower gas space, the upper gasspace communicating with the pneumatic powering system and the lower gasspace communicating with the patient breathing circuit wherein moisturefrom said patient circuit collects on the lowermost side of saidflexible diaphragm, said diaphragm being responsive to a negativepressure signal in said patient circuit to transmit said signal to saidpneumatic powering system.

1. In anesthesia ventilating apparatus of the type including a patientbreathing circuit; a bellows in said breathing circuit adapted to expandand contract to cycle gas to the patient circuit, a bellows chambersurrounding said bellows; a pneumatic powering system for cyclicallypressurizing said chamber to cause the expansion and contraction of saidbellows; and a highly flexible diaphragm mounted intermediate the saidpatient circuit and said pneumatic powering system and adapted to bedisplaced by a negative pressure signal from said patient circuit toeffect a negative pressure signal to said pneumatic powering system fortriggering cycling of said pneumatic system; the improvement comprisinga diaphragm chamber containing said flexible diaphragm, said diaphragmseparating said chamber into first and second separate gas spaces, saidfirst gas space being located above said flexible diaphragm andcommunicating with said pneumatic powering system, and said secondchamber being located below said flexible diaphragm and communicatingwith said patient circuit whereby moisture within said patient circuitcollects on the bottom of said flexible diaphragm and drains downwardlytherefrom.
 2. Apparatus in accordance with claim 1 wherein saiddiaphragm chamber is mounted above and exterior of said bellows chamber.3. Apparatus in accordance with claim 1 wherein said flexible diaphragmis circular and has its periphery sealed to the interior of saidenclosed chamber.
 4. An anesthesia ventilator for delivering gas to apatient comprising: a patient circuit; a head; a cylindrical bellowschamber depending from said head, having its upper peripheral rim sealedto said head and being closed at its lower end; a collapsible bellowssuspended within said chamber for delivering fluid to said patientcircuit and having its upper open end sealed to said head; a flexiblediaphragm mounted on top of said head, having its bottom surface incommunication with said patient circuit, and its top surface incommunication with said bellows chamber, said flexible diaphragm adaptedto flex upon sensing a negative pressure in the patient circuit totransmit the negative pressure to said bellows chamber; a pneumaticpowering system communicating with said bellows chamber and adapted torespond to a negative pressure in said bellows chamber to pressurizesaid bellows chamber and thereby force said bellows to collapse wherebygas within said bellows is forced into the patient circuit; normallyopen valve means venting the patient circuit, said valve means adaptedto sense the increased pressure in said bellows chamber to close saidvalve means.
 5. In anesthesia ventilating apparatus of the typeincluding a patient breathing circuit; a bellows in said breathingcircuit adapted to expand and contract to cycle gas to the patientcircuit; a bellows chamber surrounding said bellows; a pneumaticpowering system communicating with said bellows chamber for cyclicallypressurizing said chamber to cause the expansion and contraction of saidbellows; the improvement comprising: a diaphragm chamber, a flexiblediaphragm separating said chamber into an upper gas space and a lowergas space, the upper gas space communicating with the pneumatic poweringsystem and the lower gas space communicating with the patient breathingcircuit wherein moisture from said patient circuit collects on thelowermost side of said flexible diaphragm, said diaphragm beingresponsive to a negative pressure signal in said patient circuit totransmit said signal to said pneumatic powering system.